1. Field of the Invention
The present invention relates to a disk drive apparatus for recording (writing) and/or reproducing (reading) an information signal by rotating an optical disk, and moving an optical pick-up device along an information recording face of the optical disk. More particularly, the invention relates to a head feed mechanism suitable for use in the disk drive apparatus.
2. Description of Related Art
Optical disk drive apparatuses for recording and/or reproducing information to and/or from an optical disk are conventionally known. The so-called optical disk may be, for example, a CD (compact disk), a CD-ROM (read only memory) or the like, or an optical magnetic disk (OD) or the like. In the conventional disk drive apparatus, an optical disk is horizontally loaded onto a turntable, fixed to a rotary shaft of a spindle motor, and is rotated. Simultaneously, a laser beam is vertically irradiated on an information recording face of the optical disk by means of an optical head of an optical pick-up device. By moving the optical head from the center of the optical disk toward its outside, in the radial direction, the information signal is written to the information recording face and the information signal previously recorded on the information recording face is read out.
In such a disk drive apparatus, it is necessary to attach, within a predetermined tilt range, the information recording face of the optical disk, on which the information signal is recorded, and the optical head of the optical pick-up device, provided for reading the information. The reason is that the tilt of the optical head greatly affects the reproduction accuracy of the information signal. In this case, it is desired that an optical axis of an objective lens of the optical head should be set perpendicular with respect to the information recording face. Doing so allows recording on and/or reproduction from the optical disk with high density and precision. However, the tilt of the optical disk, the alignment of the spindle motor, and the alignment of the objective lens and the like, have variations. Therefore, it is difficult to precisely set the optical axis of the objective lens perpendicular with respect to the information recording face.
For this reason, in the disk drive apparatus in which the optical disk such as a CD, a CD-ROM or the like is used as an information recording medium, the standard tolerance of a relative tilt angle between the optical disk and the objective lens is unified within a range of 1.2xc2x0 or less (the standard tilt angle of the optical disk ranges within 0.6xc2x0 or less, and the standard tilt angle of each of the spindle motor and the objective lens on the optical disk device side ranges within 0.6xc2x0 or less). With a state in which the optical disk is fixed in a predetermined position as a reference, the optical pick-up device is tilted, thereby adjusting the optical axis of the objective lens within the range of a determined tilt.
A disk drive apparatus having such a disk tilt mechanism is shown, for example, in FIG. 14. The disk drive apparatus 1 comprises a spindle chassis 2 formed of a plate-shaped frame member having an almost square opening formed on the inside thereof, and a pick-up chassis 3 formed of a plate-shaped frame member having an opening formed therein. The pick-up chassis 3 is slightly smaller than that of the spindle chassis 2. The pick-up chassis 3 is provided with a pair of shaft portions 3a projecting from both sides in the left to right direction, while the spindle chassis 2 is provided with a pair of bearing portions 2a for rotationally supporting the shaft portions 3a. By the combination of the pair of bearing portions 2a and the shaft portions 3a, the pick-up chassis 3 is rotationally supported in the front to rear direction with respect to the spindle chassis 2.
A tilt driving mechanism 4 is provided on one side of the spindle chassis in the front to rear direction. By the actuation of the tilt driving mechanism 4, the pick-up chassis 3 is rotated in the front to rear direction of the spindle chassis 2. A spindle motor 5 is fixed, with its rotary shaft turned upward, on the other side, in the front to rear direction, of the spindle chassis 2. A turntable 6, on which the optical disk is to be loaded, is fixed integrally with the rotary shaft of the spindle motor 5.
A guide shaft 3b and a guide portion (not shown) are fixed to the pick-up chassis 3 in parallel with each other at a predetermined interval so as to be extended in the front to rear direction. A slide member 8 of an optical pick-up device 7 is slidably supported on the guide shaft 3b and the guide portion, and a rack (not shown) is fixed to the slide member 8. A gear positioned at an end of a head feed mechanism 9 is engaged with the rack. By driving the head feed mechanism 9 to transmit a rotary force to the slide member 8, the optical pick-up device 7 is moved toward and away from the turntable 6.
Additionally, a tilt sensor 10, which detects the tilt angle of the information recording face of the optical disk loaded on the turntable 6, is mounted on the slide member 8. The tilt sensor 10 emits a light toward the information recording face, and detects the warp of the optical disk on receipt of the light reflected by the information recording face. Based on the result of the detection of the tilt sensor 10, the tilt of the pick-up chassis 3 can be changed. Adjusting the pick-up chassis 3 tilt thereby adjusts the tilt of the optical axis of an optical head 7a of the optical pick-up device 7 with respect to the tilt of the information recording face.
In such a conventional disk drive apparatus, however, a pair of guide shafts 3b and guide portions movably support the optical pick-up device 7. The rack attached to the slide member 9 of the optical pick-up device 7 is engaged with the gear, at the end of the head feed mechanism 9, provided in the pick-up chassis 3. The driving force of the head feed mechanism 9 is transmitted to the rack, thereby moving the optical pick-up device 7 toward and away from the turntable 6. Therefore, a reduction gear having a plurality of gears is required, and the number of parts to be used increases, thus the structure is non-economical. Moreover, the size of the whole device is increased.
Therefore, to eliminate the above-mentioned drawbacks, a feed mechanism utilizing the combination of a stepping motor and a feed shaft has been provided. With this feed mechanism, the stepping motor is coupled to the feed shaft, thereby making the axial direction of the feed shaft coincident with that of the rotary shaft of the stepping motor. The stepping motor is fixed to a pick-up chassis through a motor holder and the tip end portion of the feed shaft is rotationally supported on the pick-up chassis via a separate bearing member. Accordingly, with such a feed mechanism, the conventional reduction gear is not required. In addition, the stepping motor can be made compact. Thus, the feed mechanism is effective in eliminating the above-mentioned drawbacks.
However, because the stepping motor generates a small torque, it is necessary to precisely align the motor and the bearing member. For this reason, aligning the stepping motor and the feed shaft is a complicated and time-consuming task to perform. Furthermore, because the bearing member is a separate part, this results in a non-economical increase in the number of parts. In addition, if the alignment precision of the stepping motor and the feed shaft is poor, the load to the stepping motor may increase, thereby causing defective actuation.
It is therefore an object of the present invention to provide a disk drive apparatus having a bearing portion for a feed shaft formed integrally with a base chassis to rotationally support the feed shaft on the bearing portion, and a head feed mechanism suitable for use in the disk drive apparatus.
In one aspect of the present invention a head feed mechanism comprises a base chassis, an optical pick-up device, and a pick-up feed mechanism. The base chassis rotationally supports a turntable on which an optical disk for recording and/or reproducing information is loaded. The optical pick-up device causes an optical head to face the optical disk loaded on the turntable in order to write and/or read the loaded information. The pick-up feed mechanism has a feed shaft for moving the optical pick-up device toward and away from the turntable, and the feed shaft is supported on a bearing portion provided integrally with the base chassis.
In an additional aspect of the present invention, a disk drive apparatus comprises a disk tray, a base chassis, an optical pick-up device, and a pick-up feed mechanism. The disk tray delivers an optical disk for recording and/or reproducing information to a disk loading position. The base chassis rotationally supports a turntable on which the optical disk is mounted. The optical pick-up device causes an optical head to face the optical disk attached to the turntable in order to write and/or read the information. The pick-up feed mechanism has a feed shaft for moving the optical pick-up device toward and away from the turntable, the feed shaft is supported on a bearing portion being provided integrally with the base chassis.
In a further embodiment of the present invention, a head feed mechanism for a disk drive assembly comprises a spindle chassis, a pickup chassis, a drive unit, and a drive shaft. The pickup chassis is rotationally supported on the spindle chassis, and includes a bearing portion integrally formed in a first portion of the pickup chassis. The drive unit is supported on the pickup chassis proximate a second portion of the pickup chassis, the second portion being positioned opposite the first portion. The drive shaft has first and second ends, the first end being supported by the integrally formed bearing portion and the second end being supported by the drive unit.
In yet a further aspect of the present invention, a spindle chassis for a disk drive assembly head feed mechanism includes first and second side structural members, front and rear structural members, an opening, a bearing portion, first, second and third holes, shaft portions, and a cam piece. The first side structural member and a second side structural member are arranged opposite each other in a first plane. The front structural member and rear structural member are arranged opposite each other in a second plane that is perpendicular to the first plane. The opening is defined by at least the first, second, third and fourth structural members. The bearing portion integrally formed in a first portion of said first side structural member. The first hole is formed in a second portion of the first side structural member, and is positioned opposite the bearing portion. The second and third holes are formed in opposite ends of the second side structural member. The shaft portions extend perpendicularly outward from the first and second side structural members. The cam piece protrudes from the second side structural member and in a direction perpendicular to the front structural member.